Fastening device for securing flexible sheet material

ABSTRACT

A fastening device, or clamp, for attaching margins of a pair of flexible sheets is provided. The clamp comprises a first strand and a second strand extending along the margins of the sheets. The first and second strands are periodically resiliently biased toward one another to clamp the overlapping margins of the sheets therebetween. The first strand can be straight, while the second strand can undulate. The first strand and the second strand can comprise metallic wires. In one embodiment, the clamp comprises a gripping member that is a resilient C-shaped clamp configured to snap flexible sheets about a substantially straight strand. The clamp preferably is used to attach adjacent flexible sheets to a structural element of a greenhouse.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The embodiments disclosed herein generally relate to fastening devices for securing flexible sheet material. In particular, the embodiments disclosed herein relate to clamps for attaching portions of flexible sheet material used in the agricultural industry.

2. Description of the Related Art

In the agricultural industry, particularly in the greenhouse industry, a means to secure flexible sheet materials is important. Greenhouses are typically constructed from glass plates or plastic sheets. Greenhouses that use plastic commonly comprise frames which are covered with portions of large flexible, plastic sheets that require some type of fastening mechanism to secure the sheets to one another and to the frame of the greenhouse.

Known mechanisms for attaching flexible sheet material generally do not allow for one portion of a flexible sheet to be fastened to another portion of a sheet in a continuous manner, such as by employing a wire, a wire-rope, or a common rope that can be suspended and attached between frame elements of a greenhouse or other structures. Many known fastening mechanisms employ a two-part locking mechanism comprising a lower locking element and an upper locking element. In such devices, the lower locking element has a relatively wide base and must be attached to a beam of the greenhouse frame. Accordingly, such known fastening mechanisms often have a relatively bulky construction and may be difficult, or even impossible, to use in certain agricultural applications. As a result, the greenhouse frame might have to be modified or customized in order to receive the two-part locking mechanism.

In addition, the large plastic sheets defining the housing of the greenhouse typically should be replaced every year or so in order to maintain the greenhouse in optimal working condition. Two-part locking mechanisms used to attach these plastic sheets can be difficult and time-consuming to disassemble. Consequently, a user may have to spend a significant amount of time disassembling the locking mechanism in order to periodically replace the flexible sheets.

SUMMARY OF THE INVENTION

An object of the embodiments disclosed herein is to provide a fastening device, such as a clamp, which can securely attach margins of flexible sheets to a structural element in a simple and efficient manner in, for example, a greenhouse or a structure for harvesting produce.

Accordingly, one aspect of the present invention involves a clamp to attach overlapping margins of a pair of sheets comprising a first strand extending along said margins and adjacent to one of said pair of sheets and a second strand extending along said margins and adjacent to the other of said pair of sheets, wherein said first and second strands are periodically resiliently biased toward one another to clamp said overlapping margins therebetween.

Another aspect involves a method of attaching overlapping margins of a pair of sheets comprising wrapping said margins between a pair of strands, one of which is substantially linear.

In another aspect of the present invention, a clamp is provided to attach overlapping margins of a pair of sheets, the clamp comprises a substantially straight strand extending along said margins and adjacent to one of said pair of sheets and a resilient gripping member configured to snap said margins around said substantially straight strand.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will now be described in connection with preferred embodiments of the invention shown in the accompanying drawings. The illustrated embodiments, however, are merely an example and are not intended to limit the invention. The drawings include the following eleven figures, which can be briefly described as follows:

FIG. 1 is a perspective view of a fastening device, such as a clamp, for attaching overlapping margins of a pair of flexible sheets.

FIG. 2 is a right side elevational view of the clamp of FIG. 1 and a tension member, such as a structural member of a greenhouse, wherein the clamp is attached to the tension member.

FIG. 3 is a top plan view of the clamp and the tension member of FIG. 2.

FIG. 4 is a bottom view of the clamp and the tension member of FIG. 2.

FIG. 5 is a front sectional view of the clamp and the tension member of FIG. 2 when viewed in direction 5-5 as shown in FIG. 3.

FIG. 6 is a right side elevational view of the clamp and the tension member of FIG. 2 and a pair of flexible sheets, wherein the clamp attaches margins of the sheets to one another and to the tension member.

FIG. 7 is a left side elevational view of the clamp, tension member, and pair of flexible sheets of FIG. 6.

FIG. 8A is a front sectional view of the clamp, tension member, and pair of flexible sheets of FIG. 6 when viewed in the direction 8-8 as shown in FIG. 6.

FIG. 8B is a front sectional view of an embodiment of a C-shaped clamp, tension member, and pair of flexible sheets when viewed in the direction 8-8 as shown in FIG. 6.

FIG. 9 is a perspective view illustrating one application of the fastening device of FIG. 1, wherein the fastening device secures adjacent flexible sheets to the frame of a greenhouse.

FIG. 10 is an enlarged view of a portion of the greenhouse of FIG. 9, wherein the fastening device, such as a clamp, attaches margins of adjacent sheets to a structural element of the greenhouse.

FIG. 11 is a perspective view illustrating another application of the fastening device of FIG. 1, wherein the fastening device secures margins of flexible sheets to a structure used in harvesting produce such as strawberries.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described more fully hereinafter with reference to accompanying drawings, in which preferred embodiments are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and exemplary of the scope of the invention to those skilled in the art. For example, the clamp disclosed herein can be used in a variety of applications in the agricultural industry beyond the applications explicitly described below.

As shown in FIG. 1, a fastening device 10 for securing flexible sheet material is provided. The fastening device 10, which may also be referred to as a clamp or strand, comprises a flexible member that can be formed into the configuration as shown in FIG. 1. In one embodiment, the clamp 10 is comprised of a resilient metallic strand or rod, such as a wire. In another embodiment, the clamp 10 comprises a metallic rod that is coated with plastic. In other embodiments, the fastening device 10 could be comprised of a group of wires (such as a cable), a flexible cord (such as a rope), or a hybrid wire-rope type material. The fastening device could be comprised of a metallic material, a plastic material, or any other suitable material that preferably has at least some degree of resiliency so that it resiliently retains a configuration similar to the configuration illustrated in FIG. 1.

The clamp 10 comprises a plurality of substantially straight spacers 20, 22 and a plurality of loops 30, 32, or undulated spacers, that function as gripping members to secure portions of adjacent flexible sheets to a tension member. In particular, the clamp 10 comprises a plurality of first spacers 20 and a plurality of second spacers 22. Each of the plurality of first spacers 20 is attached to each of the plurality of second spacers 22 by a first loop or undulated spacer 30. Similarly, each of the plurality of second spacers 22 is attached to each of the plurality of first spacers 20 by a second loop or undulated spacer 32. The first spacers 20, also referred to as the front spacers, are generally forwardly disposed with respect to the second spacers 22 when the clamp 10 is positioned in the configuration as shown in FIG. 1. Accordingly, the first loops 30 extend from a terminal end of the first spacers 20 and undulate rearward toward the second spacers 22, also referred to as the rear spacers. The rear spacers 22 extend from a terminal end of the first loops 30 and extend to the second loops 32. The second loops 32 undulate forward toward the front spacers 20. The second loops 32 and the first loops 30 are preferably configured in a similar loop-like configuration as illustrated in FIG. 1.

Therefore, in one embodiment, the clamp 10 comprises a plurality of front spacers 20 and a plurality of rear spacers 22, which are connected to each other at one end by a plurality of first loops 30 and at another end by a plurality of second loops 32. As will be described in greater detail below, the clamp 10 is configured in this manner in order to provide a simple gripping mechanism that can securely attach overlapping margins of flexible sheets to one another and to a tension member, such as a structural element. In some applications, this configuration of the fastening device 10 could provide a stronger attachment of margins of adjacent flexible sheets when compared to known fastening devices. The fastening device 10 is adapted for use in a variety of applications, such as in greenhouses and in structures used to harvest strawberries and other produce.

Continuing with reference to FIG. 1, in one embodiment, the fastening device 10 is constructed from a substantially straight, elongate strand of metallic wire. In this embodiment, the clamp 10 is formed manually by an operator to a desired configuration. The operator can simply shape and form the elongate strand of wire to create a clamp 10 having the desired characteristics disclosed herein for securing sheet material in general and, in particular, for securing overlapping margins of adjacent flexible sheets in greenhouses and similar applications. In other embodiments, the fastening device 10 can be formed using other techniques such as, for example, by using a wire-bending machine or a similar automated shaping device.

With reference to FIG. 2, the fastening device 10 is shown attached to a tension member 40. The tension member 40 can be used in combination with the clamp 10 to secure margins of adjacent sheet material. In one embodiment, the tension member 40 comprises a substantially straight strand of metallic wire. In some applications, for instance, the tension member 40, or strand, can comprise a frame element or a beam of a greenhouse or a structural element of a system for harvesting produce. The tension member 40 illustrated herein has an elongate, cylindrical configuration; however, the tension member 40 can comprise a variety of forms and configurations. For example, in some applications, the tension member 40 could have a generally rectangular, elliptical, or oblong cross-section.

FIG. 2 shows the clamp 10 attached to the tension member 40. The front spacers 20 and the rear spacers 22 are disposed substantially longitudinal to the tension member 40. It should be noted that when the clamp or strand 10 is viewed from the particular perspective shown in FIG. 2, the front spacers 20 (or first spacers) are generally disposed in the rear of the tension member or strand 40 and the rear spacers 22 (or second spacers) are generally disposed in the front of the tension member 40. It can be seen that the first loops 30 and the second loops 32 at least partially wrap around the exterior surface of the tension member 40 to secure the clamp 10 to the tension member 40. Advantageously, the loops 30, 32 have a smaller diameter than the tension member 40 to resiliently snap the clamp 10 in place about the tension member 40.

In the particular view illustrated in FIG. 2, the rear spacers 22 are shown near an upper surface of the tension member 40 slightly in front of the front spacers 20 of the clamp 10. The first loops 30 and the second loops 32 extend from the terminal ends of the rear spacers 22 along a front surface of the tension member 40. The first loops 30 and second loops 32 continue to extend around a lower surface of the tension member 40 and at least partially around a rear surface of the tension member 40. The loops 30, 32 extend to the terminal ends of the front spacers 20 along the rear surface of the tension member 40.

As shown in FIGS. 3 and 4, in one embodiment of the fastening device 10 described herein, the first spacers 20 and the second spacers 22 are disposed substantially parallel to one another longitudinally along an exterior surface of the tension member 40. The first loops 30 and the second loops 32 extend around a portion of the exterior surface of the tension member 40 and connect the plurality of first spacers 20 to the plurality of second spacers 22.

In one embodiment, the clamp 10 is attached to the tension member 40 by applying a force to the clamp 10 generally transverse to the tension member 40. This can be accomplished manually by pressing the clamp 10 onto and around the exterior surface of the tension member 40 or through other suitable means such as by automated pressing techniques. When the clamp 10 is pressed onto the tension member 40, the first spacers 20 and second spacers 22 are preferably spaced apart so as to enable the tension member 40 to enter a receiving area 50 (shown in FIG. 5) defined by the first loops 30 and second loops 32. In one embodiment, the loops 30, 32 are sufficiently flexible to receive the tension member 40. Once the clamp 10 is pressed onto the tension member 40, the front spacers 20 and rear spacers 22 are preferably resiliently biased toward one another to securely fasten the clamp 10 to the tension member 40. As a result, the clamp or second strand 10 snaps into place over the tension member or first strand 40. Thus, the fastening device 10 can clamp overlapping margins of adjacent sheets so that the sheets define a substantially continuous surface.

FIG. 5 illustrates a front sectional view of the clamp 10 and the tension member 40 as viewed in direction 5-5 of FIG. 3. The clamp 10 defines a receiving area 50 capable of receiving a tension member 40 and flexible sheet material (as discussed below with reference to FIGS. 6 and 7). As shown, in one embodiment, the fastening device 10 extends substantially around the exterior surface of the tension member 40. The clamp 10 is shown having a circular cross-sectional area; however, other suitable shapes and configurations can be used for the clamp 10 and are within the scope of the embodiments for a fastening device for securing flexible sheet material disclosed herein. For example, the clamp 10 could be formed to have a rectangular cross-section, elliptical cross-section, or oblong cross-section if it is being used with a tension member having a rectangular, elliptical, or oblong shape. In addition, as noted above, the tension member can comprise a variety of shapes and configurations and is not limited to having a circular, rectangular, or elliptical cross-sectional area.

Turning now to FIGS. 6 and 7, a clamping system is illustrated comprising a pair of flexible sheets 60, 70 used in conjunction with the fastening device 10 and tension member 40. FIG. 6 shows a right side view of the clamping system, while FIG. 7 shows a corresponding left side view of the system. In FIG. 6, a first sheet 60 is shown on a right side of the tension member 40. An exterior margin 62 of the first sheet 60 is wrapped about the tension member 40 within the receiving area 50 (as shown in FIG. 5) of the clamp 10. The first sheet 60 extends vertically upward from the clamping system. A portion of a second sheet 70 can be seen extending vertically downward from a left side of the tension member 40. In FIG. 7, the second sheet 70, positioned generally on the left side of the tension member 40, is shown in greater detail. An exterior margin 72 of the second sheet 70 is at least partially wrapped around the tension member 40. Preferably, at least a portion of the margin 72 of the second sheet 70 overlaps a portion of the margin 62 of the first sheet 60 within the receiving area of the clamp 50 (as shown in FIG. 5). The second sheet 70 extends vertically downward from the clamping system. A portion of the first sheet 60 can be seen extending vertically upward from the right side of the tension member 40. The flexible sheets 60, 70 can be a variety of sizes and can be composed of a variety of materials. In one embodiment, the flexible sheets 60, 70 are about twenty feet wide and thirty feet long and are composed of a plastic material or a mesh material.

As indicated above, the sheets 60, 70 have exterior margins 62, 72 that are wrapped about the tension member 40 and, preferably, at least partially overlap one another. Once the overlapping margins 62, 72 of the sheets 60, 70 are placed around the tension member 40, the clamp 10 can be pressed about the exterior margins 62, 72 and the tension member 40. As a result, the clamp 10 can snap into place and securely attach the sheets 60, 70 to one another about the tension member 40. The first spacers 20 and second spacers 22 of the clamp 10 are configured to strongly grip the overlapping margins 62, 72 of the flexible sheets 60, 70. Advantageously, a significant lateral force F₁ can be applied to the first sheet 60 and a significant lateral force F₂ can be applied to the second sheet 70, yet the clamp 10 will preferably maintain the sheets 60, 70 in an attached configuration.

FIGS. 8A and 8B illustrate a front sectional view of a fastening device 10, a tension member 40, and a pair of sheets 60, 70 as viewed in the direction 8-8 of FIG. 6. Similar to the illustration of FIG. 5, FIG. 8A shows that the clamp 10 comprising a plurality of spacers 20, 22 and a plurality of loops 30, 32 can extend substantially around the exterior surface of the tension member 40. The first sheet 60 extends outward from one side of the tension member 40, while the second sheet 70 extends outward from another side of the tension member 40. The clamp 10 can comprise a resilient gripping member configured to snap the margins of the first sheet 60 and the second sheet 70 about the tension member or substantially straight strand 40. In one embodiment, as shown in FIG. 8B, the fastening device 10 can comprise an elongate, resilient C-shaped clamp that clips onto the tension member 40. For example, the C-shaped clamp can comprise a piece of resilient tubing slit along its length. In this embodiment, the fastening device 10 preferably secures flexible sheets 60, 70 in a similar manner to that described heretofore with respect to an embodiment of a clamp 10 comprising a plurality of spacers 20, 22 and a plurality of loops 30, 32.

FIGS. 9 and 10 illustrate an application of the fastening device for use in greenhouses. A greenhouse 100 is typically comprised of a series of structural or frame elements 110 and a series of covering members 120, wherein the covering members 120 attach to the frame elements 110 to provide a substantially enclosed environment for cultivating plants and the like. In some greenhouses, the covering members 120 comprise large, flexible sheets.

The fastening device 130 can be used to clamp exterior margins of adjacent sheets 120 to the structural elements 110 of the greenhouse 100. As shown in FIG. 9, the frame elements 110 extend the length of the greenhouse 100. The frame elements 110 can be a variety of shapes and sizes. In the illustrated embodiment, the frame elements are substantially round rods, wires, or tension members. Greenhouses commonly have frame elements 110 also extending across the width of the greenhouse; however, such frame elements are not shown in FIG. 9 and are not necessary to describe how the clamp 130 operates in the greenhouse 100. Sheets 120 extend between adjacent frame elements 110 and must be secured to each other and to the frame of the greenhouse 100 in a suitable manner. The clamp 130 provides a means to secure adjacent sheets to the frame of the greenhouse.

As shown in the enlarged view in FIG. 10, exterior margins of adjacent flexible sheets 120 a, 120 b are positioned about a particular frame element 110 of the greenhouse. Once the sheets 120 a, 120 b are in place, the clamp 130 can be pressed onto the frame element 110 to securely attach the flexible sheets 120 a, 120 b (in the manner described above with respect to FIGS. 2 through 8). When a user of the greenhouse 100 chooses to replace the flexible sheets 120 a, 120 b, which may be required relatively often, or to remove them for some other reason, the user can simply detach the clamp 130 from the greenhouse 100 by pulling opposing sides or spacers away from each other and removing the clamp 130. Advantageously, the clamp 110 allows a user of the greenhouse to quickly and easily attach flexible sheets to each other and to detach sheets from one another.

FIG. 11 shows another application of the fastening device for use in harvesting produce, such as strawberries. Fruits and vegetables are typically harvested from the ground using natural soil. However, in some instances, it is desirable to harvest produce in an elevated configuration so that the produce is not in direct contact with the earth.

An elevated harvesting arrangement 200 can comprise a series of posts 210 configured in a T-shape and used to support the harvesting system 200. A series of flexible sheets 220 can run through the series of posts 210. The flexible sheets 220 are preferably arranged in a generally cylindrical configuration and define a receiving area 230. Growing media, such as soil and the like, can be inserted into the receiving area 230 to provide an environment conducive to growing certain fruits and vegetables. A tension member 240, such as a cylindrical rod or wire, also runs the length of the series of posts 210 and supports the flexible sheets 220. Strawberries 260, for example, can extend from the growing media and out of openings in the flexible sheets 220 so that the strawberries 260 lay along portions of the exterior surface of the sheets 220.

In one embodiment, the fastening device 250 can be used to secure the flexible sheets 220 to the tension member 240. The fastening device 250 preferably provides a sufficiently strong attachment of the flexible sheets 220 to the rod 240 so that the flexible sheets can securely hold growing media, which can be quite heavy. Other configurations of the harvesting arrangement 200 are possible. Accordingly, the clamp 250 can be used in a variety of harvesting systems 200 to securing attach flexible sheets so as to facilitate cultivating produce when at least partially raised from the ground.

Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. For example, the fastening device disclosed herein can be formed in a variety of shapes and configurations and can be used to secure margins of sheets to a variety of forms of wires or tension members. In addition, the clamp described herein can be used in applications beyond greenhouses and structures used to harvest produce. For example, the clamp can be used in water tanks or reservoirs to attach flexible sheets, which often line the shell of such tanks and/or reservoirs, so as to contain water within the water tank by preventing water from penetrating the adjacent sheets. Thus, the clamp can be used to waterproof the interior shell of water reservoirs.

In addition, while a number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. For example, in some embodiments, the fastening device could be used to attach flexible sheets to one another without use of a tension member, such as in the water tank application described in the preceding paragraph. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims. 

1. A clamp to attach overlapping margins of a pair of sheets, said clamp comprising: a first strand extending along said margins and adjacent to one of said pair of sheets; and a second strand extending along said margin and adjacent to the other of said pair of sheets, said first and second strands periodically resiliently biased toward one another to clamp said overlapping margins therebetween.
 2. A clamp as defined in claim 1, wherein said second strand is periodically biased toward alternating, opposed sides of said first strand.
 3. A clamp as defined in claim 1, wherein said first strand is straight and said second strand undulates.
 4. A clamp as defined in claim 1, wherein said first strand and said second strand each comprise metallic wires.
 5. A clamp as defined in claim 1, wherein said first strand and said second strand each comprise metallic wire coated with plastic.
 6. A clamp as defined in claim 1, wherein said second strand clamps said overlapping margins of said sheets about said first strand.
 7. A clamp as defined in claim 6, wherein said second strand defines a substantially circular receiving area to receive said margins and said first strand.
 8. A clamp as defined in claim 1, wherein said first strand comprises a tension member.
 9. A clamp as defined in claim 8, wherein said second strand comprises a first spacer, a first loop, a second spacer, and a second loop to clamp said overlapping margins of said sheets about said tension member such that said first loop and said second loop extend substantially around the exterior surface said tension member.
 10. A clamp as defined in claim 9, wherein said spacers and said loops define a receiving area to receive said margins and said tension member.
 11. A method of attaching overlapping margins of a pair of sheets, said method comprising: wrapping said margins between a pair of strands, one of which is substantially linear.
 12. The method of claim 11 further comprising clamping said pair of strands to said margins to attach said pair of sheets.
 13. The method of claim 11 further comprising wrapping said margins about one of said pair of strands that comprises a tension member.
 14. The method of claim 13 further comprising clamping said pair of strands to said margins to attach said pair of sheets.
 15. The method of claim 11 further comprising wrapping said margins about a frame element of a greenhouse; and clamping said pair of strands to said margins and said frame element to attach said pair of sheets to the frame of said greenhouse.
 16. A clamp to attach overlapping margins of a pair of sheets, said clamp comprising: a substantially straight strand extending along said margins and adjacent to one of said pair of sheets; and a resilient gripping member configured to snap said margins around said substantially straight strand.
 17. A clamp as defined in claim 16, wherein said gripping member is resiliently biased toward said substantially straight strand to clamp said margins around said substantially straight strand.
 18. A clamp as defined in claim 16, wherein said substantially straight strand comprises a metallic wire.
 19. A clamp as defined in claim 16, wherein said gripping member comprises an elongate, resilient C-shaped clamp.
 20. A clamp as defined in claim 16, wherein the gripping member attaches said sheets about a structural element of a greenhouse. 